May 20, 2025 — The perinatal healthcare system in the U.S. is not prepared to treat patients impacted by wildfire smoke in a timely manner , according to the first study on this issue. Michel Boudreaux, PhD, Associate Professor of Health Policy and Management at the University of Maryland, and colleagues report a substantial burden of wildfire smoke to pregnant people and their infants in Medical Care , the official journal of the Medical Care Section of the American Public Health Association , published in the Lippincott portfolio by Wolters Kluwer .
"The smoke-plumes generated by wildfires can be transported over large distances and affect nearly every community in the U.S., even those far from fire activity," the researchers explain. "Prenatal smoke exposure has been linked to adverse birth outcomes. Impacts on pregnant people have been less well studied, but the pollutants carried by smoke increase hypertensive disorders of pregnancy, gestational diabetes, and cardiovascular events."
Wildfire smoke threatens a substantial number of reproductive-age women and infants
Every day, expert analysts at the National Oceanic and Atmospheric Administration analyze information from satellite sensors to identify the geographic boundaries of wildfire smoke plumes. Dr. Boudreaux's group gathered this publicly available data along with county-level data on demographics, number of births, location of neonatal care units and maternity care hospitals, availability of OB-GYNs and family practice physicians, and smoke-attributable measures of PM2.5, a major air pollutant. The variables were averaged for the years 2016 to 2020.
The average annual number of smoke-days ranged from 3.8 in low-risk counties to 15.3 in high-risk counties. Counties on the west coast had the highest numbers (more than 35 days/year in the most affected counties), but the northern Rockies and portions of the Midwest also tended to have an elevated number of smoke-days, typically 10 to 25 days/year. The average PM2.5 concentration was more than doubled in high-risk counties compared with low-risk counties (6.6 vs. 3.0 mcg/m3).
In an average year during the study period, 7.3 million women of reproductive age lived in the high-risk counties and 460,496 infants were born in them. In counties with moderate levels of wildfire smoke exposure, the respective figures were 20 million and 1.1 million.
High-risk communities have substantial resource constraints
Compounding the broad exposure to wildfire smoke, perinatal resource distribution differed significantly according to smoke-risk category. For example:
- Median number of OB-GYNs per 10,000 births—61 in low-risk counties, 33 in moderate-risk counties, and 0 in high-risk counties
- Median distance to nearest maternity care hospital—8, 13, and 22 miles
- Median distance to nearest neonatal intensive care unit—34, 44, and 72 miles
After adjustment for race, age, poverty, uninsurance, and rurality—sociodemographic factors typically used to identify medically underserved areas—these associations were attenuated but still statistically significant. "Communities at high risk of smoke exposure appeared to be particularly constrained, beyond what their other characteristics would predict," the authors comment.
"Public health measures such as clean air refuges, sealing homes, and distributing respirators and air filters can help patients mitigate the increasing threat of wildfire smoke," Dr. Boudreaux and his colleagues continue. "However, millions of reproductive age women and their infants are being exposed and many will need timely treatment. Policymakers and clinicians seeking to meet the challenges of climate change must consider these constraints in devising appropriate responses."
Read Article: Perinatal Health Care Resources and Wildfire Smoke
